Crystalline forms of intermediates for carbapenem antibiotics are desirable from a stability and purity standpoint. These compounds facilitate the synthesis of carbapenem antibiotics on a commercial scale.
In the present invention, crystalline forms of the compound 2S-cis-3-[[(4-mercapto-2-pyrrolidinyl)carbonyl]-amino]benzoic acid have been discovered and characterized. Crystalline 2S-cis-3-[[(4-mercapto-2-pyrrolidinyl)carbonyl]-amino]benzoic acid and pharmaceutically acceptable salts and solvates thereof are disclosed. The compounds can generally be synthesized taking into account the disclosure of U.S. Pat. No. 5,478,820 granted on Dec. 26, 1995. This patent does not disclose the side chain in crystalline form.